A new study (Boulila et al., 2022) suggests “abrupt and severe changes in Earth’s past climate” have been occurring at ~1,500-year periodicities since the iceless Jurassic period.
Warming events of degrees C per within decades or less were at one time thought to have occurred only at locations like Greenland and the North Atlantic during the last glacial period (70 to 12 thousand years ago).
But the evidence has been piling up from locations throughout the globe (e.g., on continents and tropical to high latitude oceans, lakes, and rivers) indicating these warming events have “a global interconnection between the two hemispheres.”
These “abrupt and severe” global warming events with ~1,500-year periodicities can even be traced back to the iceless Jurassic period when Antarctica was a rainforest and 38°C warmer than today. This suggests the driving force for these global warming periods were not dependent on ice sheet dynamics.